Abrasive articles

ABSTRACT

Abrasive belts suitable for offhand and automated article finishing provide a uniform finish without lapping or parting lines. The belts comprise a lofty non-woven web securely needle tacked to a woven backing and impregnated with resin and abrasive.

United States Patent Legacy et a1.

[ 1 Sept. 5, 1972 ABRASIVE ARTICLES [72] Inventors: Lloyd W. Legacy, White Bear Lake; Thomas R. McAvoy, Stillwater; Leonard E. Nelson, Saint Paul, all of Mich.

73 Assignee: Minnesota Mining and Manufacturing Company, St. Paul, Mich.

22 Filed: Dec.l1, 1970 21 Appl. No.: 97,185

[52] US. Cl. ..51/400, 51/404 [51] Int. Cl ..B24d 3/00, 324d 1 1/02 [58] Field of Search.....5l/400, 404,407; 161/80, 81

[56] References Cited UNITED STATES PATENTS 6/1967 Stein .5 1/4 Q0 2,404,207 7/ 1946 Ball ..51/400 2,593,373 4/1952 Weber ..161/80 X 3 ,280,5 1 7 10/ 1 966 Copeland ..51/400 3,284,872 11/1966 Closson ..l61/81 X 3,117,905 l/l964 Smith ..16l/8l X Primary Examiner-Dona.ld G. Kelly Attorney-Kinney, Alexander, Sell, Steldt & Delahunt [57] ABSTRACT Abrasive belts suitable for offhand and automated article finishing provide a uniform finish without lapping or parting lines. The belts comprise a lofty non-woven web securely needle tacked to a woven backing and impregnated with resin and abrasive.

7 Claims, 2 Drawing Figures ABRASIVE ARTICLES BACKGROUND OF THE INVENTION This invention relates to abrasive belts.

Lofty, open, low-density, fibrous, non-woven abrasive belts have been found useful in offhand and automated finishing of various articles of wood, brass, aluminum, steel, etc. because they provide a long, con- 1 tinuous striking pattern and uniform finish without lapping or parting lines, all without need for belt oscillation. Additionally, such open belts are relatively nonloading and cool running.

Attempts to make commercially suitable lofty, open, low-density belts having reasonable work life together with adequate abrasiveness have been disappointing. Unsupported belts made from lofty non-woven abrasive such as those disclosed in U.S. Pat. No. 2,958,593, while non-loading and cool running, stretch excessively and are not sufficiently durable to provide an adequate work life. Attempts to make supported lofty, open belts from tufted carpets and the like provide belts which load up with abraded filings and which are not cool running. Attempts to make supported lofty, open belts by adhesively laminating lofty, open, non-woven fibrous abrasive to support backings have been disappointing because the resultant laminate has low resistance to snagging on articles being finished and easily delaminate during use. U.S. Pat. No. 3,324,609 describes various attempts to overcome low snag resistance by needle tacking the non-woven abrasive into a support web. Specifically, ordinary needle tacking is disclosed to be inadequate. The patent then discloses a technique of locking non-woven abrasive article to the support backing by fusing the needle-tacked fibers. However, fusing the fibers degrades them and tenacity of the bond between the backing and the non-woven abrasive portion is still less than satisfactory for offhand and automated finishing of manufactured articles. The

non-woven abrasive portion delaminates from the backing after a few minutes of use.

Accordingly, lofty, open low-density, fibrous, nonwoven abrasive belts which provide a long, continuous, striking pattern and uniform finish without lapping or parting lines, are relatively non-loading and cool running, but yet having a commercially reasonable work life together with adequate abrasiveness', have not been available. Belts known in the art have lacked one or more of the previously mentioned properties.

SUMMARY The invention provides lofty, open, low-density, fibrous, non-woven abrasive belts suitable for offhand and automated finishing of various articles of wood, brass, aluminum, steel, etc. The belts of the invention provide a long, continuous striking pattern and uniform finish without lapping or parting lines, are relatively non-loading and cool running, have a commercially reasonable work life together with adequate abrasiveness. Offhand finishing of various articles of wood, brass, aluminum, steel, etc. is readily automated and commercially accomplished in a quick, efficient, economical manner because of the aforementioned properties and the belts long life. A lofty, open, lowdensity, fibrous, non-woven abrasive layer is securely attached to a support backing such that it has excellent 0 tacked into and partially through a dimensionally stable scrim cloth comprising multifilarnent woven synthetic fibers.

BRIEF DESCRIPTION OF THE DRAWING In the drawing, FIG. 1 is a perspective view of a lofty, open, low-density, non-woven, abrasive belt of the invention;

FIG. 2 is an enlarged side elevational view of the abrasive belt of FIG. 1 showing the non-woven portion thereof securely extending into and partially through the woven portion.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The supporting backing portion of the abrasive belt 10 of the invention comprises a dimensionally stable woven scrim cloth 11 comprising multi-filament tensilized synthetic organic fibers. Synthetic organic fibers capable of withstanding the temperatures at which impregnating resins are cured without deterioration are satisfactory; for example, nylon and polyester. The fibers should be tensilized by orientation and must be multi-filament. The woven scrim should have a relatively open weave to provide a cool running belt and to permit impregnating resin and abrasive to thoroughly wet the article and interlock the fibers. It has been found that a minimum of five. threads per inch is satisfactory if the tensile strength of the scrim is at least lbs/lineal inch and does not stretch more than 5 percent, preferably 2 percent at tensile loadings up to 25 lbs/inch.

The lofty, open, low-density, fibrous, non-woven web portion 12 of the belt 10 may be of any synthetic fiber such as nylon, polyester, etc., capable of withstanding the temperatures at which the impregnating resins are cured without deterioration. The fibers are tensilized by orientation and crimped. Fibers found satisfactory for the non-woven portion are about 0.75 to about 4, preferably about 1.5 to about 2.5 inches in length and should have a denier of about 1.5 to 500, 15 to 100 being preferred. If desired, fibers of mixed denier may be used to obtain a desired scratch pattern. Also, use of larger fibers permits use of larger abrasive particles. The non-woven web 12 is readily formed on a Rando- Weber machine (commercially available from the Curlator Corporation) or may be formed by other conventional carding procedures. It has been found that the non-woven portion of the belt should comprise'at least about 40, preferably 60 grains per 24 sq. inches. Lesser amounts of fiber provide belts having a commerci'ally inadequate work life. These fiber weights typically provide a web, before needling or addition of abrasive, having a thickness on the order of about 0.25 to about 3, preferably about 1 inch.

The non-woven web 12 is secured to the woven scrim 11 by means of needle tacking. The amountor degree of needle tacking found necessary to provide useful belts is that which secures the non-woven web to the scrim so that a minimum of 5 lbs/inch is necessary to separate them. This has been found to be at least about 100, preferably at least about 125 needle penetrations per square inch of scrim when X 18 X 25 X 3.5 RB needles are used with a penetration depth of seveneights inch through the scrim. This degree of needle tacking provides an article in which about 60 percent of the fiber thickness 12 is above scrim l1 and 40 percent of the fiber thickness 13 is below scrim ll. Suitable belts have been obtained when the thickness ratio of fiber above the scrim to fiber below the scrim is from about 0.75 to 3, preferably about 1.0 to 1.7. Lesser delamination strengths provide articles which fail by delamination during severe use. The needle tacking is readily accomplished by use of a conventional needle loom such as that commercially available from the James Hunter Machine Company.

Following needle tacking, the article is impregnated with a resin-abrasive slurry to thoroughly saturate the scrim fibers and the non-woven web fibers. The resin, when dried, aids in securing the non-woven fibers to the scrim. Preferred resins are those which are relatively hard and which provide a delamination strength of non-woven fibers from the scrim of at least 15 pounds per inch. Resins found satisfactory are such as phenolformaldehyde, epoxy, polyurethane, urea-formaldehyde, etc., and are the resins commonly utilized in making non-woven, low-density abrasives. The resinabrasive slurry is preferably applied by means of a 2- roll coater which simultaneously applies resin from both sides of the web to provide thorough impregnation. For mineral coated belts satisfactory for use in articie finishing, it has been found that the non-woven surface of the belt should have a Shore A durometer of about 25 to 75 as measured with a 3/16 inch instrument foot. A lower durometer provides a belt easily snagged and torn by sharp corners, etc. on the articles being finished. Articles of greater durometer are excessively dense, load up with pieces of abradant, perform like a sandpaper, and do not provide the excellent uniform finish of non-woven abrasives.

The abrasive particles utilized are those of 24 grade and finer normally used for a finishing operation and comprise such as aluminum oxide, silicon carbide, talc, cerium oxide, garnet, flint, emery, etc. If desired, the commonly used metal working lubricants such as greases, oils, stearates, and the like may be utilized with the belts of the invention.

The following example, in which all parts are by weight unless otherwise indicated, further illustrates the lofty, open, low-density, fibrous, non-woven abrasive belts of the invention without limitation thereof.

EXAMPLE 1 A 40 inch wide lofty, open, non-woven air laid web of a 50/50 blend of 1.5 inch lS-denier per filament and 2 inch 50 denier per filament oriented nylon 66 fibers was prepared by (1) initially blending and opening the fibers with a weigh-feeder (commercially available from the Procter and Schwartz Company) and then with a fiber opener (commercially available from the Dilts and Kennedy Company) to provide a lofty mass of fibers. The finished air laid web was made with a Rando-Weber machine (commercially available from the Curlator Corporation) and had a weight of 59 grains per 24 sq. inches. The non-woven air laid mat was then placed upon a 16 X l6 plain weave nylon mesh scrim having a total denier of 840 per thread (commercially available from the Burlington Industrial Fabrics Company). The combined article was then passed through a needle felting machine (commercially available from the James Hunter Machine Company, Division of Crompton Knowles Corporation) at a rate of 5 feet per minute, the needle felting machine being fitted with a needle board having 23 rows of needles spaced 0.43 inches apart with a distance between needles in a single row of 0.5 inches. The needle board was fitted with 15 X 18 X 25 X 3.5 RB needles (commercially available from the Torrington Company) and was operated at a rate of I punches per minute with a seven-eights inch penetration depth. The resultant composite structure had about 60 percent of its thickness above the center line of the scrim cloth and about 40 percent of its thickness below the center line. The needled fibers were mechanically interlocked to the scrim and could not be removed without destroying the scrim.

The needled composite was impregnated with the following resin-abrasive slurry by passing it through a two roll coater.

31.0 Parts The solution viscosity was adjusted to LEOO ,300 cps by addition of cellosolve acetate.

The side of the composite having the greater thickness of fibers was in contact with the top roll of the two roll coater and the bottom roll was immersed in a trough containing the abrasive-adhesive slurry. The top roll was supplied with the same abrasive-adhesive slurry by means of a metering roll.

After coating, the abrasive-adhesive coating was cured in an air impingement oven until dry and nontacky (about 320 F. for 6 minutes). The dried article contained 169 grains of the abrasive-adhesive composition per 24 sq. inches.

A final abrasive-adhesive slurry was spray coated on the thicker top surface of the laminate and dried at 250290 F. for 3 minutes and cured at 3l0-320 F. for 10 minutes in an air impingement oven. The dry coating weight of the spray was 78 grains per 24 square inches and the spray composition was:

Ethylcellosolve 21.0 Parts A-stage base-catalyzed phenol-formal- The solution viscosity was adjusted to 280 cps by addition of ethylcellosolve.

The resultant dried web was slit into a 3 inch strip, skived, and spliced into an endless belt. The belt was fitted on a Hammond Robot Lathe machine and used to abrade round one-half inch by 6 inch 1018 rolled steel bars. The machine was set at 60 pounds of work piece pressure, timed for three minutes per bar, and operated at 1,750 rpm, or 6,411 surface feet per minute. The belt was found to satisfactory abrade more than 60 grams of steel in 6 cycles of 3 minutes each. The belt provided a uniform finish without lapping or parting marks and did not load up with observable quantities of abraded steel. Additionally, the belt was cool running and not even warm when touched.

We claim:

1. An abrasive article of manufacture comprising in combination:

a. a dimensionally stable woven scrim comprising woven multi filament tensilized synthetic organic fibers, said scrim having at least 5 threads per inch and a tensile strength of at least 100 lbs. per inch,

. a lofty, open, low-density, fibrous, non-woven web comprising at least about 40 grains per 24 sq. inches of tensilized synthetic organic fibers securely interlocked into and partially through said scrim, such that the thickness ration of non-woven fiber on one side of the scrim center line to nonwoven fiber on the opposite side of said scrim center line is from about 0.75:1 to 25:1, and

c. a resinous composition thoroughly impregnating the fibers and interstices of said scrim and said non-woven web, said resin securely adhering abrasive particles thereto, whereby to provide in said article a delamination strength of at least 15 lbs. 5 per inch.

2. Article of claim 1 in the form of an endless belt.

3. Belt of claim 2 wherein said scrim comprises nylon fibers and said non-woven web comprises nylon fibers.

4. Belt of claim 3 wherein said resin is a cured polyu- 10 rethane and said abrasive is aluminum oxide.

5. Article of claim 1 wherein the scrim comprises nylon fibers and said non-woven web comprises nylon fibers.

6. Article of claim 5 wherein said resin is a cured l5 urethane, and said abrasive is aluminum oxide.

7. An endless belt comprising in combination:

a. a dimensionally stable endless woven scrim comprising woven multi-filament tensilized nylon fibers, said scrim having at least 5 threads per inch and a tensile strength of at least 100 lbs. per inch,

. a lofty, open, low-density, fibrous, non-woven web comprising at least 40 grains per 24 sq. inches of tensilized nylon fibers securely interlocked into d artiall th ou h said 5 rim, such t t t e fi iick ess ra e o no%1-woven t iber on one siife sa id scrim centerline to non-woven fiber on the opposite side of said scrim centerline is from about 0.7521 to 2.5:1,

c. a cured urethane resin thoroughly impregnating the fibers and interstices of said scrim and said non-woven web securely adhering said non-woven web to said scrim with a delamination strength of at least pounds per inch,

d. aluminum oxide abrasive particles dispersed throughout the fibers of said non-woven web and securely adhered to said fibers by said resin, and

e. a resin-abrasive mixture dispersed throughout and adhered to the non-woven fibers on the exterior of said belt, said resin comprising the cured reaction a I I l UNITED STATES PATENT OFFICE CERTIFICATE OF CORETEON ,688A53 Dated September 5, 97

Patent No.

lnventor(s) Lloyd w. Legacy, Thomas R. McAvoy and Leonard E. Nelson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

[72 Inventors: "all of Mich." should be "all of Minn."

Paul, Mich." should be "St. Paul, Minn."

F737 Assignee: "St.

(,laim 1, line 38 "ration" should be "ratio" Signed and sealed this 6th day of February 1973.

(SEAL) Attsst:

EDWARD MeFLETGHhJR ,JR. RUERT GOTTSCHALK Attssting Qfficer Commissioner of Patents USCOMM-DC 60376-PB9 U45. GOVERNMENT PRINTING OFFICE: IBGQ 0-366-384 

2. Article of claim 1 in the form of an endless belt.
 3. Belt of claim 2 wherein said scrim comprises nylon fibers and said non-woven web comprises nylon fibers.
 4. Belt of claim 3 wherein said resin is a cured polyurethane and said abrasive is aluminum oxide.
 5. Article of claim 1 wherein the scrim comprises nylon fibers and said non-woven web comprises nylon fibers.
 6. Article of claim 5 wherein said resin is a cured urethane, and said abrasive is aluminum oxide.
 7. An endless belt comprising in combination: a. a dimensionally stable endless woven scrim comprising woven multi-filament tensilized nylon fibers, said scrim having at least 5 threads per inch and a tensile strength of at least 100 lbs. per inch, b. a lofty, open, low-density, fibrous, non-woven web comprising at least 40 grains per 24 sq. inches of tensilized nylon fibers securely interlocked into and partially through said scrim, such that the thickness ratio of non-woven fiber on one side said scrim centerline to non-woven fiber on the opposite side of said scrim centerline is from about 0.75:1 to 2.5:1, c. a cured urethane resin thoroughly impregnating the fibers and interstices of said scrim and said non-woven web securely adhering said non-woven web to said scrim with a delamination strength of at least 15 pounds per inch, d. aluminum oxide abrasive particles dispersed throughout the fibers of said non-woven web and securely adhered to said fibers by said resin, and e. a resin-abrasive mixture dispersed throughout and adhered to the non-woven fibers on the exterior of said belt, said resin comprising the cured reaction product of a phenol-formaldehyde resin and an amine. 